I do credit card charges on my iPhone also, great when on the road.

AroundMe is one of my favorites for travel: it gives distance, location and directions to all the nearest coffee shops, banks, gas stations, hospitals, hotels, movie theatres, parking, pharmacies, supermarkets, taxis, stage theaters, and more.

The Google App (not the web page) is a unique app: you just say into the microphone what you want to know, and it gets you the answer. Works quite well in my experience.

And when I hear some music on the radio that I really like, I just click on Shazam; it recognizes not just the music but also the specific recording and gives me all the CD info.

The Weather channel app was very helpful when I did my road trip through Washington and Oregon (I even drove through Nehalem!), where they have actual weather...

And my wife really liked the BubbleWrap app (it's a game, I take it I don't have to explain...:O).

[If you have trouble with teenagers, use the Aggravate app to stop whatever they're doing, while not bothering adults too much :O)

But my all time favorite 3rd party app is Evernote. It serves as my knowledge base in the office and on the road. I need not even give a thought to synchronization and backup, it's all handled wirelessly without user intervention. A truly great and very well designed app, it handles text notes (including web pages), voice notes, photo notes, and lots more.

AT&T offers customers at every Starbucks nationwide free Wi-Fi for iPhones (everyone else pays). This is great for downloading heavy duty podcasts and such.